茂金属聚乙烯结构与拉伸性能的研究

借助GPC、FTIR、WAXD、密度梯度计和万能材料试验机等测试手段,研究了茂金属聚乙烯结构与拉伸性能,发现茂金属聚乙烯(mPE)具有比传统聚乙烯更规整的结构、更窄的分子量分布以及更高的断裂拉伸强度,并且密度数据显示乙烯-辛烯共聚物mPE-2分子结构中含有长支链,乙烯-己烯共聚物(mPE-4)则属于典型的中、高密度聚乙烯,这使两者的结晶结构存在一定差别,前者具有较低的结晶度和较小的晶粒尺寸,而后者拥有较高的结晶度和较大的晶粒尺寸;此外,与传统聚乙烯相比,茂金属聚乙烯还表现出明显的“应变硬化”现象。

Structure and tensile properties of metallocene polyethylenes

The structure and tensile properties of metallocene polyethylenes (mPE) were studied by means of a series of modern analysis techniques such as GPC, FTIR, WAXD, tensile experiments and so on. It was found that mPEs had higher tacticity, narrower molecular weight distribution and higher ultimate tensile strength than traditional ones, and the density data implied that there were some long chains in the structure of mPE 2, while mPE 4 was proved to be a kind of mid or high density polyethylene. Because of the difference of mPE's chain structures, their crystalline structures were quite different in that mPE 2 had lower crystallinity and smaller crystallite size, and mPE 4 showed higher crytallinity and larger crystallite size. By addition, compared with traditional polyethylenes, mPEs exhibit obvious "Strain Hardening" phenomena.